\documentclass[10pt]{article} % required
\pagestyle{empty} % required
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{color}
\usepackage[T1]{fontenc}

\begin{document}\definecolor{fgC}{rgb}{0,0,0}\color{fgC}\[\begin{matrix}
 U_t = R(U)  \Leftrightarrow U_t = F(U)_x \\ 
 U = \begin{bmatrix}
 \rho \\ 
 \rho u \\
 \rho E
 \end{bmatrix}\;\;\;
 F(U) = \begin{bmatrix}
 \rho u \\ 
 \rho u^2 + p \\
 \rho u H
 \end{bmatrix} 
 \end{matrix}\]\end{document}